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A135541
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a(n)=2a(n-1)-a(n-2)+2a(n-3).
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0
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0, 2, 7, 12, 21, 44, 91, 180, 357, 716, 1435, 2868, 5733, 11468, 22939, 45876, 91749, 183500, 367003, 734004, 1468005, 2936012, 5872027, 11744052, 23488101, 46976204, 93952411, 187904820, 375809637, 751619276, 1503238555, 3006477108
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| O.g.f.: -7/[5(2x-1)]-(4x+7)/[5(x^2+1)]. a(n) = [7*2^n-(-1)^[n/2]*A010712(n+1)]/5 . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 23 2008
a(n)=-[7/10-(2/5)*I]*I^n+(7/5)*2^n-[7/10+(2/5)*I]*(-I)^n, with n>=0 and I=sqrt(-1) - Paolo P. Lava (paoloplava(AT)gmail.com), Jun 09 2008
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CROSSREFS
| Cf. A007909, A007910, A016029, A134658.
Sequence in context: A023669 A137401 A119713 * A180804 A122264 A079824
Adjacent sequences: A135538 A135539 A135540 * A135542 A135543 A135544
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KEYWORD
| nonn
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), Feb 22 2008
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EXTENSIONS
| More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 23 2008
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